This is stupid and pointless. No one here ACTUALLY has the means to check scientifically how stiff their frame is, let alone even really tell a difference between frame X and frame Y which is stiffer. Something as small as a slightly higher tire PSI will be mistaken for a bike seeming stiffer because it rides harder. There are just too many other variable to just guess like this.

Anyway... nearly all oversized, overbuilt modern carbon frames are plenty stiff for you. If you need stiffer, go custom.

The stiffest bb measured by Zedler/tour has been the Specialized Tarmac at 72Nmm. Then there are quite a few bikes measured at 71Nmm. The Cannondale mentioned is actually quite compliant in the bb area but very stiff around the headtube where the S/W ratio is calculated.I said has been.A few days ago Zedler Institute measured a carbon bike at 91Nmm bb stiffness.

In all honesty it doesn't really matter as long as it is stiff enough to not ghost shift (so don't buy a Merida Scultura).

Get a frame that fits well. Test ride a few. See which ones you like. The bike that rides the best may not be the 'stiffest' bike.

Also, if you're trying to save weight, pick a light frame. Otherwise, ignore the weight, since frames are all 'light' at the top end these days and since it makes the heart of the bike, save weight elsewhere.

The stiffest bb measured by Zedler/tour has been the Specialized Tarmac at 72Nmm. Then there are quite a few bikes measured at 71Nmm. The Cannondale mentioned is actually quite compliant in the bb area but very stiff around the headtube where the S/W ratio is calculated.I said has been.A few days ago Zedler Institute measured a carbon bike at 91Nmm bb stiffness.

Results from RoadBike.de results from some time ago, pretty different testing methodologies if the 72N/mm is the highest value achieved

I don't agree about you comment about preferences in BB stiffness. The main problem is that with traditional double diamond frames you are coupling BB stiffness with rear end compliance, the parameter that many riders use to define frame comfort. In my book, a stiffer BB is always positive

We use the Zedler no:s because they are widely accepted industry standards. They have also tested hundreds of bikes using the same protocol for years making for a huge base if data. We don't agree on the absolute relevance on how he calculates the bb stiffness, but it is the current apples to apples test.

Comfort is indeed a different spec mainly defined by flex on the seattube / post. But as as you know bb stiffness is not about the bb flexing but rather the down tube and chainstays bending torsionally. Also the infamous vertical compliance in the main triangle is factored in the Zedler bb flex figure. Torsional flex in the downtube may also give some bump absorbing properties (comfortableTi frames).

Comfort can come from two approaches, isolating the bike (vertical compliance of the rear end) or isolating the rider (seat tube flex)

andy2 wrote:

But as as you know bb stiffness is not about the bb flexing but rather the down tube and chainstays bending torsionally. Also the infamous vertical compliance in the main triangle is factored in the Zedler bb flex figure.

It's the first time that I hear about vertical compliance of the main triangle. Can you comment in detail how they factor this figure?

If you pm me we can go into detail about this.Zedler factors the vertical component along with the sideway component (pendulum movement) of the bb. The top tube will flex some under vertical load, yes.

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